My father was using a program (Brazil IRS official tax filing app) in his computer. There was a corrupted file that crashed the system, the OS gave the option to reinstall it and he took it. He didn't lose any file in the Documents folder or Desktop, but all the programs and apps were gone including Thunderbird.

Are the messages that he stored gone? I know that Thunderbird keeps those files in update/Roaming/Thunderbird/Profiles but a fear that the old update folder was wiped. I already reinstalled Thunderbird and relogged his old e-mail account.